A prior art technique for detecting the presence of a delta modulated digital signal is described in co-pending application Ser. No. 830,256, entitled "A Delta Modulation Detector", by Paul H. Horn, filed on Sept. 2, 1977 and assigned to the instant assignee. According to this technique, the statistical characteristics of a delta modulated digital signal are utilized to make a one time determination as to the presence of the digital signal. The delta modulated signal is determined to be present if over a predetermined time interval, the number of bit transitions of the delta modulated digital signal is greater than a predetermined high number or less than a predetermined low number. However, this technique is insensitive to error bursts, has a slow response time and does not provide a continuous monitor of the presence of the delta modulated digital signal.